How about deflating tyres so you can push some thin rope (washing line?) down bead, then when you have finished pull out while blowing with an airline?
Many moons ago I used to work for a blasting company and we used to do a lot of cheap facing up of alloy wheels for youngsters with silly cars. We left the tyres on and our painter would mask up and paint. Can't say we ever had a problem with grit in the bead. If air can't out then it is unlikely that grit will get in.
Kev
while I'm sure there will be no problem blasting the wheels with the tyres on. (You probably know how hard it is to bread the bead from the rim) all the problems I've had with alloy wheels is due to deterioration of the paint film where the tyre bead sits causing slow punctures. I think it is a better job to do all the wheel including the inside.
I agree, lots of alloys generally leak from where the tyre sits on the rim, They tend to flake there.
If it was me i'd do the whole rim.
But it depends on wether your just tarting it up to sell or wether your keeping it
the majority of the wheels i used to blast. the tires were left on .steel and ally depended how much the punter wanted to pay there was no problem grit getting in the bead where tire sealed if the tires were decent just leave em on if they wernt take them off it all depended how coroded the ally was weather to remove or not
We have a tyre bay, alloy wheels and steel wheels do frequently loose air from between rim inner lip and the tyre bead due to rust flake/scabs on steels and a kinda oxidisation of alloys that form scads and lift the rubber bead off the rim allowing air past slowly. Also the rate of air loss depends on what position the bad rim is standing. All the referb alloys I have enquired about only refinish and spray/laquer the outside visible area of the wheel, this would not solve any air loss problems due to rim corrosion!
Remove the tyre to work on the rim and do inside the rim/beads seating edge. You dont want any swarf or grit material inside the tyre. If you must leave tyre on the inflate it as much as you dare keeping the pressure BELOW the marked on max pressure this will keep the bead tight on the rim